• 한국항공운항학회지
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• 제19권1호
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• pp.1-6
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• 2011

The free-wing tilt-body aircraft is researched in the flight performance characteristics such as short take-off and landing capability, and reduced sensitivity to gust and center of gravity (CG) change. Due to the main wing separating from the fuselage, the high tiltable empennage, and the stub-wing strongly influencing from the propeller wake, the resulting vehicle aerodynamics and flight dynamics are quite different from those of a conventional fixed-wing aircraft. Using the governing flight dynamics model was studied previously, all of speed and body tilt angle is simulated to determine the flight envelope by a non-linear 3-DOF flight simulation analysis. Though flight performance and trimmability are studied, the flight model of free-wing tilt-body aircraft is to reduce the hidden risk and to achieve the successful flight test. It is analyzed the flight characteristics that distinguishes free-wing tilt-body aircraft from the conventional aircraft.

• Journal of Biosystems Engineering
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• 제28권2호
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• pp.97-106
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• 2003

One of the obstructing factors against managing dairy fm has been heavy labor requirement for feeding dairy cows. A Power-tiller TMF mixer was developed to reduce the cost and to provide economic benefit. The TMF mixer was desisted by the feeding capacity of 20∼30 heads at a batch with various functioning systems of auger type mixer, delivery conveyer, weighing console, pipe heater type heating system, power transmission train and mounting trailer. According to the study resulted, it showed that 1,200rpm, 1,600rpm, 2,000rpm and 2,300rpm were 6ps. Bps, lops and 12ps respectively. and that reduced shaft output by 15%. On the fodder mixer attached powertiller, initial output was necessary large torque. And the heating system was maintaining uniform temperature 60$^{\circ}C$ relatively.

• International Journal of Aeronautical and Space Sciences
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• 제3권2호
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• pp.13-23
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• 2002

In this paper, we present a sliding mode control strategy for the re-orientation maneuver of rigid spacecraft containing rotating wheels. The wheels are considered as internal devices, and external inputs are employed for generation of control commands. The formulation is developed for a general case while particular example is applied to pitch bias momentum spacecraft with a single momentum wheel. The resultant control commands are used to take the gyroscopic effects into account which are caused by the rotating wheels. The controller designed demonstrates that the nutational motion of the pitch bias momentum spacecraft is effectively controlled. It is also assumed that the external control torque device is of on-off nature, and pulse width modulation technique is applied to construct proper control torque history.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2000년도 추계학술대회 및 발표대회 강연 및 발표논문 초록집
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• pp.11-12
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• 2000

Non-stoichiometric ceramics of $Ni_{x}ZnO_{1-x}Fe_{2}O_{4}$ were prepared by self-propagating high temperature synthesis reaction with various processing conditions and their stoichometric numbers were determined by neutron diffraction. The neutron diffraction patterns were measured at room temperature using monochromatic neutrons with a wave length of 0.18339 nm from a Ge(331) mocochromator at a 90 degree take off angle. The Rietveld refinement of each pattern converged to good agreement (x2=1.88-2.24). The neutron diffraction analysis revealed the final stoichiometries of the ferrites were $Ni_{0.38}Zn_{0.62}Fe_{2}O_{4}$ and $Ni_{0.33}Zn_{0.67}Fe_{2}O_{4]$, respectively. This supports that final stoichiometric number of the self-propagating high temperature synthesis product can be controlled by the processing parameters during the combustion reaction.

• Journal of Communications and Networks
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• 제10권3호
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• pp.233-238
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• 2008

In this paper, the application of genetic algorithms (GAs) for orthogonal frequency division multiplexing (OFDM) signal peak-to-average power ratio (PAPR) reduction is investigated. A GA is applied in order to enhance the performance of some known techniques for OFDM PAPR reduction and the potential benefits are analyzed. Using the proposed techniques, the system designer can take advantage of the GA versatility, robustness, and adaptability to specific system requirements, in order to achieve a convenient trade-off between effectiveness and computational burden.

• 한국철도학회논문집
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• 제10권2호
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• pp.161-166
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• 2007

Recently, The business environment is very rapidly changed and complicated. Therefore, the companies are confront with the biggest difficulty. To overcome this difficulty, the management should be able to accomplish the human resources management and the efficient business management. Korea railroad industry has a close association with national life as it carries out public works based on its public nature as well as purses the corporate spirit. For that reason, Korea railroad industry has a great spin-off on national economy and exerts a tremendous impact on the improvement of productivity around the industries and the international competitiveness at aspect of efficiency resulting from business rationalization. Railroad system can be described as organic. Railroad Employs take a great role in this system. According the psychology and the Organization Behavior, the decision maker's personality and employee' work satisfaction have influence on performance. The purpose of this study is to examine the Railroad Employs' Personality and Work satisfaction which influence on the efficient business management.

• 제어로봇시스템학회논문지
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• 제17권2호
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• pp.102-107
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• 2011

In this paper we present cooperation of heterogeneous robot team, composed of a wheeled robot and a helicopter for localization and map building. This heterogeneous robot team can successfully fulfill task by combining the abilities of both robots than single robot because wheeled robot and helicopter have complementing ability. The scenario describes a tightly cooperative task, where the wheeled robot move carrying the helicopter and detect obstacles, if there are obstacles, helicopter take off for map building and land, then robot team move destination avoiding obstacles. We present PID controller for position control of helicopter and transformation algorithm to global coordinate from image pixel coordinate. Experimental result show that the proposed method is valid.

• 전자공학회논문지A
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• 제33A권7호
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• pp.261-268
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• 1996

Hardware-software codesign becomes improtant to effectively sagisfy perfomrance goals, because designers can trade-off in the way hardware and software components work teogether to exhibit a specified behavior. In this paper, a hardware-software pratitioning algorithm is presetned, in which the system behavioral description containing a mixture of hardware and software components is partitioned into hardware part and software part. The partitioning algorithm tries to minimize the given cost function under constraints on hardware resources or latency. Recursive moving of operations between the hardware and software parts is used to find a near optimum partition and the list scheduling approach is used to estimate the hardware area and latency. Since memory may take substantial protion of the hardware part, memory cost is included in sthe hardware cost. Experimental resutls show that our algorithm is effective.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2003년도 제21회 추계학술대회 논문집
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• pp.215-218
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• 2003

본 연구에서는 회전익 상태에서 이/착륙, 저속 전진비행을 하고, 고정익 상태에서 고속 전진비행을 하는 스마트 무인기 추진시스템을 모델링하고 회전익 모드, 고정익 상태의 고속 비행모드, 팁 제트 노즐과 주 엔진 노즐을 모두 이용하는 혼합모드에 대해 정상상태 성능해석을 수행하였다.

• 항공우주기술
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• 제11권2호
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• pp.158-163
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• 2012

구형비행체는 기존의 항공기와 달리 비행체가 원형 프레임으로 보호되는 구조로 되어있다. 항우연에서 개발중인 본 비행체(Flying Ball)는 수직이착륙 및 정지비행이 가능한 배터리로 구동되는 프로펠러를 장착하고 있으며 실내외에서 운용이 가능하도록 개발이 진행중이다. 최종적으로는 자율비행이 가능토록 하여 정찰용이나 감시용으로 활용할 수 있도록 할 예정이다.